[v2,02/23] interconnect: fix icc_provider_del() error handling

Commit Message

Johan Hovold March 6, 2023, 7:56 a.m. UTC

The interconnect framework currently expects that providers are only
removed when there are no users and after all nodes have been removed.

There is currently nothing that guarantees this to be the case and the
framework does not do any reference counting, but refusing to remove the
provider is never correct as that would leave a dangling pointer to a
resource that is about to be released in the global provider list (e.g.
accessible through debugfs).

Replace the current sanity checks with WARN_ON() so that the provider is
always removed.

Fixes: 11f1ceca7031 ("interconnect: Add generic on-chip interconnect API")
Cc: [e-mail]      # 5.1: 680f8666baf6: interconnect: Make icc_provider_del() return void
Reviewed-by: Konrad Dybcio <[e-mail]>
Signed-off-by: Johan Hovold <[e-mail]>
---
 drivers/interconnect/core.c | 14 ++------------
 1 file changed, 2 insertions(+), 12 deletions(-)

Comments

Luca Ceresoli March 7, 2023, 9:43 a.m. UTC | #1

On Mon,  6 Mar 2023 08:56:30 +0100
Johan Hovold <[e-mail]> wrote:

> The interconnect framework currently expects that providers are only
> removed when there are no users and after all nodes have been removed.
> 
> There is currently nothing that guarantees this to be the case and the
> framework does not do any reference counting, but refusing to remove the
> provider is never correct as that would leave a dangling pointer to a
> resource that is about to be released in the global provider list (e.g.
> accessible through debugfs).
> 
> Replace the current sanity checks with WARN_ON() so that the provider is
> always removed.
> 
> Fixes: 11f1ceca7031 ("interconnect: Add generic on-chip interconnect API")
> Cc: [e-mail]      # 5.1: 680f8666baf6: interconnect: Make icc_provider_del() return void
> Reviewed-by: Konrad Dybcio <[e-mail]>
> Signed-off-by: Johan Hovold <[e-mail]>

[Tested on i.MX8MP using an MSC SM2-MB-EP1 Board]
Tested-by: Luca Ceresoli <[e-mail]>

Patch

diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c
index 5217f449eeec..cabb6f5df83e 100644
--- a/drivers/interconnect/core.c
+++ b/drivers/interconnect/core.c
@@ -1065,18 +1065,8 @@  EXPORT_SYMBOL_GPL(icc_provider_add);
 void icc_provider_del(struct icc_provider *provider)
 {
 	mutex_lock(&icc_lock);
-	if (provider->users) {
-		pr_warn("interconnect provider still has %d users\n",
-			provider->users);
-		mutex_unlock(&icc_lock);
-		return;
-	}
-
-	if (!list_empty(&provider->nodes)) {
-		pr_warn("interconnect provider still has nodes\n");
-		mutex_unlock(&icc_lock);
-		return;
-	}
+	WARN_ON(provider->users);
+	WARN_ON(!list_empty(&provider->nodes));
 
 	list_del(&provider->provider_list);
 	mutex_unlock(&icc_lock);